Handlebars:
Template
{{#list people}}{{firstname}} {{lastname}}{{/list}}
Preparation-Script
Handlebars.registerHelper("list", function(items, options) {
  const itemsAsHtml = items.map(item => "<li>" + options.fn(item) + "</li>");
  return "<ul>\n" + itemsAsHtml.join("\n") + "\n</ul>";
});
Input
{
  people: [
    {
      firstname: "Yehuda",
      lastname: "Katz"
    },
    {
      firstname: "Carl",
      lastname: "Lerche"
    },
    {
      firstname: "Alan",
      lastname: "Johnson"
    }
  ]
}
Output
<ul>
<li>Yehuda Katz</li>
<li>Carl Lerche</li>
<li>Alan Johnson</li>
</ul>